Ultrasonic device for cutting and coagulating

ABSTRACT

A surgical apparatus comprises a body, an ultrasonic transducer, a shaft, and an end effector. The ultrasonic transducer is operable to convert electrical power into ultrasonic vibrations. The shaft couples the end effector and the body together. The end effector comprises an ultrasonic blade in acoustic communication with the ultrasonic transducer. The ultrasonic blade includes a recess region having a plurality of recesses. The recess region is tapered such that the cross-sectional area of the recess region decreases along the length of the recess region. The ultrasonic blade is also curved such that a central longitudinal axis of the ultrasonic blade extends along a curved path. A reference circuit is used to account for voltage drops of unknown values during operation of the surgical apparatus.

PRIORITY

This application claims priority to U.S. Provisional Pat. App. No.61/640,227, entitled “Ultrasonic Device for Cutting and Coagulating,”filed Apr. 30, 2012, the disclosure of which is incorporated byreference herein.

This application also claims priority to U.S. Provisional Pat. App. No.61/722,986, entitled “Ultrasonic Device for Cutting and Coagulating,”filed Nov. 6, 2012, the disclosure of which is incorporated by referenceherein.

BACKGROUND

A variety of surgical instruments include an end effector having a bladeelement that vibrates at ultrasonic frequencies to cut and/or sealtissue (e.g., by denaturing proteins in tissue cells). These instrumentsinclude piezoelectric elements that convert electrical power intoultrasonic vibrations, which are communicated along an acousticwaveguide to the blade element. The precision of cutting and coagulationmay be controlled by the surgeon's technique and adjusting the powerlevel, blade edge, tissue traction and blade pressure.

Examples of ultrasonic surgical instruments include the HARMONICACE®Ultrasonic Shears, the HARMONIC WAVE® Ultrasonic Shears, theHARMONIC FOCUS® Ultrasonic Shears, and the HARMONIC SYNERGY® UltrasonicBlades, all by Ethicon Endo-Surgery, Inc. of Cincinnati, Ohio. Furtherexamples of such devices and related concepts are disclosed in U.S. Pat.No. 5,322,055, entitled “Clamp Coagulator/Cutting System for UltrasonicSurgical Instruments,” issued Jun. 21, 1994, the disclosure of which isincorporated by reference herein; U.S. Pat. No. 5,873,873, entitled“Ultrasonic Clamp Coagulator Apparatus Having Improved Clamp Mechanism,”issued Feb. 23, 1999, the disclosure of which is incorporated byreference herein; U.S. Pat. No. 5,980,510, entitled “Ultrasonic ClampCoagulator Apparatus Having Improved Clamp Arm Pivot Mount,” filed Oct.10, 1997, the disclosure of which is incorporated by reference herein;U.S. Pat. No. 6,325,811, entitled “Blades with Functional BalanceAsymmetries for use with Ultrasonic Surgical Instruments,” issued Dec.4, 2001, the disclosure of which is incorporated by reference herein;U.S. Pat. No. 6,773,444, entitled “Blades with Functional BalanceAsymmetries for Use with Ultrasonic Surgical Instruments,” issued Aug.10, 2004, the disclosure of which is incorporated by reference herein;and U.S. Pat. No. 6,783,524, entitled “Robotic Surgical Tool withUltrasound Cauterizing and Cutting Instrument,” issued Aug. 31, 2004,the disclosure of which is incorporated by reference herein.

Still further examples of ultrasonic surgical instruments are disclosedin U.S. Pub. No. 2006/0079874, entitled “Tissue Pad for Use with anUltrasonic Surgical Instrument,” published Apr. 13, 2006, the disclosureof which is incorporated by reference herein; U.S. Pub. No.2007/0191713, entitled “Ultrasonic Device for Cutting and Coagulating,”published Aug. 16, 2007, the disclosure of which is incorporated byreference herein; U.S. Pub. No. 2007/0282333, entitled “UltrasonicWaveguide and Blade,” published Dec. 6, 2007, the disclosure of which isincorporated by reference herein; U.S. Pub. No. 2008/0200940, entitled“Ultrasonic Device for Cutting and Coagulating,” published Aug. 21,2008, the disclosure of which is incorporated by reference herein; U.S.Pub. No. 2009/0105750, entitled “Ergonomic Surgical Instruments,”published Apr. 23, 2009, the disclosure of which is incorporated byreference herein; U.S. Pub. No. 2010/0069940, entitled “UltrasonicDevice for Fingertip Control,” published Mar. 18, 2010, the disclosureof which is incorporated by reference herein; and U.S. Pub. No.2011/0015660, entitled “Rotating Transducer Mount for UltrasonicSurgical Instruments,” published Jan. 20, 2011, the disclosure of whichis incorporated by reference herein; U.S. Pub. No. 2012/0029546,entitled “Ultrasonic Surgical Instrument Blades,” published Feb. 2,2012, the disclosure of which is incorporated by reference herein; U.S.patent application Ser. No. 13/538,588, filed Jun. 29, 2012, entitled“Surgical Instruments with Articulating Shafts,” the disclosure of whichis incorporated by reference herein; and U.S. patent application Ser.No. 13/657,553, filed Oct. 22, 2012, entitled “Flexible HarmonicWaveguides/Blades for Surgical Instruments,” the disclosure of which isincorporated by reference herein.

Additionally, some of the foregoing surgical instruments may include acordless transducer such as that disclosed in U.S. Pub. No.2012/0112687, entitled “Recharge System for Medical Devices,” publishedMay 10, 2012, the disclosure of which is incorporated by referenceherein; U.S. Pub. No. 2012/0116265, entitled “Surgical Instrument withCharging Devices,” published May 10, 2012, the disclosure of which isincorporated by reference herein; and/or U.S. Pat. App. No. 61/410,603,filed Nov. 5, 2010, entitled “Energy-Based Surgical Instruments,” thedisclosure of which is incorporated by reference herein.

While several surgical instruments and systems have been made and used,it is believed that no one prior to the inventors has made or used theinvention described in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims which particularly pointout and distinctly claim this technology, it is believed this technologywill be better understood from the following description of certainexamples taken in conjunction with the accompanying drawings, in whichlike reference numerals identify the same elements and in which:

FIG. 1 depicts a side elevational view of an exemplary ultrasonicsurgical instrument;

FIG. 2 depicts a left elevational view of an ultrasonic blade of thesurgical instrument of FIG. 1;

FIG. 3 depicts a right elevational view of the ultrasonic blade of FIG.2;

FIG. 4 depicts a top plan view of the ultrasonic blade of FIG. 2;

FIG. 5 depicts a bottom plan view of the ultrasonic blade of FIG. 2;

FIG. 6 depicts a top plan view of the ultrasonic blade of FIG. 2, withseveral cross-sectional planes indicated;

FIG. 7 depicts a cross-sectional view of the ultrasonic blade of FIG. 2,taken along line 7-7 of FIG. 6;

FIG. 8 depicts a cross-sectional view of the ultrasonic blade of FIG. 2,taken along line 8-8 of FIG. 6;

FIG. 9 depicts a cross-sectional view of the ultrasonic blade of FIG. 2,taken along line 9-9 of FIG. 6;

FIG. 10 depicts a top plan view of an exemplary alternative ultrasonicblade suited for incorporation in the instrument of FIG. 1;

FIG. 11 depicts a side elevational view of a portion of an acousticwaveguide of the surgical instrument of FIG. 1;

FIG. 12 depicts a top plan view of the portion of the acoustic waveguideof FIG. 11;

FIG. 13 depicts a schematic view of an exemplary circuit suited forincorporation in the instrument of FIG. 1;

FIG. 14 depicts a schematic view of another exemplary circuit suited forincorporation in the instrument of FIG. 1;

FIG. 15 depicts a schematic view of another exemplary circuit suited forincorporation in the instrument of FIG. 1;

FIG. 16 depicts a schematic view of another exemplary circuit suited forincorporation in the instrument of FIG. 1;

FIG. 17 depicts a schematic view of another exemplary circuit suited forincorporation in the instrument of FIG. 1;

FIG. 18 depicts exemplary output waveforms of the circuits of FIGS.15-17;

FIG. 19 depicts a schematic view of another exemplary circuit suited forincorporation in the instrument of FIG. 1;

FIG. 20 depicts exemplary output waveforms of the circuit of FIG. 19;

FIG. 21 depicts an exploded perspective view of exemplary housingcomponents that may be incorporated into the instrument of FIG. 1;

FIG. 22 depicts a partial perspective view of a first housing of thehousing components of FIG. 21;

FIG. 23 depicts a partial perspective view of a second housing of thehousing components of FIG. 21;

FIG. 24 depicts a partial side elevational view of the first housing ofFIG. 22 coupled with an exemplary retention feature;

FIG. 25 depicts a perspective view of the retention feature of FIG. 24;

FIG. 26 depicts an exploded perspective view of exemplary alternativehousing components that may be incorporated into the instrument of FIG.1;

FIG. 27 depicts a side elevational view of a first exemplary housingcomponent from the instrument of FIG. 1, with a hole formed tofacilitate separation from a second housing component;

FIG. 28 depicts a side elevational view of a second exemplary housingcomponent from the instrument of FIG. 1, with a hole formed tofacilitate separation from a first housing component;

FIG. 29 depicts a top plan view of an exemplary ultrasonic bladeassembly that may be incorporated into the instrument of FIG. 1;

FIG. 30 depicts a cross-sectional side view of the blade assembly ofFIG. 29, taken along line 30-30 of FIG. 29;

FIG. 31 depicts a top partial view of an exemplary power cableconnection assembly, with one housing half of a surgical instrumentseparated from the connection assembly and another housing half engagedwith the connection assembly; and

FIG. 32 depicts a top partial view of an exemplary power cableconnection assembly, with the housing halves secured to the connectionassembly.

The drawings are not intended to be limiting in any way, and it iscontemplated that various embodiments of the technology may be carriedout in a variety of other ways, including those not necessarily depictedin the drawings. The accompanying drawings incorporated in and forming apart of the specification illustrate several aspects of the presenttechnology, and together with the description serve to explain theprinciples of the technology; it being understood, however, that thistechnology is not limited to the precise arrangements shown.

DETAILED DESCRIPTION

The following description of certain examples of the technology shouldnot be used to limit its scope. Other examples, features, aspects,embodiments, and advantages of the technology will become apparent tothose skilled in the art from the following description, which is by wayof illustration, one of the best modes contemplated for carrying out thetechnology. As will be realized, the technology described herein iscapable of other different and obvious aspects, all without departingfrom the technology. Accordingly, the drawings and descriptions shouldbe regarded as illustrative in nature and not restrictive.

It is further understood that any one or more of the teachings,expressions, embodiments, examples, etc. described herein may becombined with any one or more of the other teachings, expressions,embodiments, examples, etc. that are described herein. Thefollowing-described teachings, expressions, embodiments, examples, etc.should therefore not be viewed in isolation relative to each other.Various suitable ways in which the teachings herein may be combined willbe readily apparent to those of ordinary skill in the art in view of theteachings herein. Such modifications and variations are intended to beincluded within the scope of the claims.

For clarity of disclosure, the terms “proximal” and “distal” are definedherein relative to a human or robotic operator of the surgicalinstrument. The term “proximal” refers the position of an element closerto the human or robotic operator of the surgical instrument and furtheraway from the surgical end effector of the surgical instrument. The term“distal” refers to the position of an element closer to the surgical endeffector of the surgical instrument and further away from the human orrobotic operator of the surgical instrument.

I. Exemplary Ultrasonic Surgical Instrument

FIG. 1 illustrates an exemplary ultrasonic surgical instrument (10). Atleast part of instrument (10) may be constructed and operable inaccordance with at least some of the teachings of U.S. Pat. No.5,322,055; U.S. Pat. No. 5,873,873; U.S. Pat. No. 5,980,510; U.S. Pat.No. 6,325,811; U.S. Pat. No. 6,773,444; U.S. Pat. No. 6,783,524; U.S.Pub. No. 2006/0079874; U.S. Pub. No. 2007/0191713; U.S. Pub. No.2007/0282333; U.S. Pub. No. 2008/0200940; U.S. Pub. No. 2009/0105750;U.S. Pub. No. 2010/0069940; U.S. Pub. No. 2011/0015660; U.S. Pub. No.2012/0112687; U.S. Pub. No. 2012/0116265; U.S. patent application Ser.No. 13/538,588; U.S. patent application Ser. No. 13/657,553; and/or U.S.Pat. App. No. 61/410,603. The disclosures of each of the foregoingpatents, publications, and applications are incorporated by referenceherein. As described therein and as will be described in greater detailbelow, instrument (10) is operable to cut tissue and seal or weld tissue(e.g., a blood vessel, etc.) substantially simultaneously. It shouldalso be understood that instrument (10) may have various structural andfunctional similarities with the HARMONIC ACE® Ultrasonic Shears, theHARMONIC WAVE® Ultrasonic Shears, the HARMONIC FOCUS® Ultrasonic Shears,and/or the HARMONIC SYNERGY® Ultrasonic Blades. Furthermore, instrument(10) may have various structural and functional similarities with thedevices taught in any of the other references that are cited andincorporated by reference herein.

To the extent that there is some degree of overlap between the teachingsof the references cited herein, the HARMONIC ACE® Ultrasonic Shears, theHARMONIC WAVE® Ultrasonic Shears, the HARMONIC FOCUS® Ultrasonic Shears,and/or the HARMONIC SYNERGY® Ultrasonic Blades, and the followingteachings relating to instrument (10), there is no intent for any of thedescription herein to be presumed as admitted prior art. Severalteachings herein will in fact go beyond the scope of the teachings ofthe references cited herein and the HARMONIC ACE® Ultrasonic Shears, theHARMONIC WAVE® Ultrasonic Shears, the HARMONIC FOCUS® Ultrasonic Shears,and the HARMONIC SYNERGY® Ultrasonic Blades.

Instrument (10) of the present example comprises a handle assembly (20),a shaft assembly (30), and an end effector (40). Handle assembly (20)comprises a body (22) including a pistol grip (24) and a pair of buttons(26). Handle assembly (20) also includes a trigger (28) that ispivotable toward and away from pistol grip (24). It should beunderstood, however, that various other suitable configurations may beused, including but not limited to a scissor grip configuration. Endeffector (40) includes an ultrasonic blade (100) and a pivoting clamparm (44). Clamp arm (44) is coupled with trigger (28) such that clamparm (44) is pivotable toward ultrasonic blade (100) in response topivoting of trigger (28) toward pistol grip (24); and such that clamparm (44) is pivotable away from ultrasonic blade (100) in response topivoting of trigger (28) away from pistol grip (24). Various suitableways in which clamp arm (44) may be coupled with trigger (28) will beapparent to those of ordinary skill in the art in view of the teachingsherein. In some versions, one or more resilient members are used to biasclamp arm (44) and/or trigger (28) to the open position shown in FIG. 1.

An ultrasonic transducer assembly (12) extends proximally from body (22)of handle assembly (20). Transducer assembly (12) is coupled with agenerator (16) via a cable (14). Transducer assembly (12) receiveselectrical power from generator (16) and converts that power intoultrasonic vibrations through piezoelectric principles. Generator (16)may include a power source and control module that is configured toprovide a power profile to transducer assembly (12) that is particularlysuited for the generation of ultrasonic vibrations through transducerassembly (12). By way of example only, generator (16) may comprise a GEN300 sold by Ethicon Endo-Surgery, Inc. of Cincinnati, Ohio. In additionor in the alternative, generator (16) may be constructed in accordancewith at least some of the teachings of U.S. Pub. No. 2011/0087212,entitled “Surgical Generator for Ultrasonic and ElectrosurgicalDevices,” published Apr. 14, 2011, the disclosure of which isincorporated by reference herein. It should also be understood that atleast some of the functionality of generator (16) may be integrated intohandle assembly (20), and that handle assembly (20) may even include abattery or other on-board power source such that cable (14) is omitted.Still other suitable forms that generator (16) may take, as well asvarious features and operabilities that generator (16) may provide, willbe apparent to those of ordinary skill in the art in view of theteachings herein.

Ultrasonic vibrations that are generated by transducer assembly (12) arecommunicated along an acoustic waveguide (150) (shown in FIGS. 11-12),which extends through shaft assembly (30) to reach ultrasonic blade(100). Blade (100) is thus operable to effectively cut through and sealtissue, particularly when the tissue is being clamped between clamp arm(44) and blade (100). It should be understood that waveguide (150) maybe configured to amplify mechanical vibrations transmitted throughwaveguide (150). Furthermore, waveguide (150) may include featuresoperable to control the gain of the longitudinal vibrations alongwaveguide (150) and/or features to tune the waveguide (150) to theresonant frequency of the system. Buttons (26) are operable toselectively activate transducer assembly (12), to thereby activateultrasonic blade (100). In the present example, two buttons (26) areprovided—one for activating ultrasonic blade (100) at a low power andanother for activating ultrasonic blade (100) at a high power. However,it should be understood that any other suitable number of buttons and/orotherwise selectable power levels may be provided.

In the present example, the distal end of ultrasonic blade (100) islocated at a position corresponding to an anti-node associated withresonant ultrasonic vibrations communicated through the waveguide, inorder to tune the acoustic assembly to a preferred resonant frequencyf_(o) when the acoustic assembly is not loaded by tissue. Whentransducer assembly (12) is energized, the distal end of ultrasonicblade (100) is configured to move longitudinally in the range of, forexample, approximately 10 to 500 microns peak-to-peak, and in someinstances in the range of about 20 to about 200 microns at apredetermined vibratory frequency f_(o) of, for example, 55.5 kHz. Whentransducer assembly (12) of the present example is activated, thesemechanical oscillations are transmitted through the waveguide to reachultrasonic blade (100), thereby providing oscillation of ultrasonicblade (100) at the resonant ultrasonic frequency. Thus, when tissue issecured between ultrasonic blade (100) and clamp arm (44), theultrasonic oscillation of ultrasonic blade (100) may simultaneouslysever the tissue and denature the proteins in adjacent tissue cells,thereby providing a coagulative effect with relatively little thermalspread. When transducer assembly (12) and ultrasonic blade (100) are notenergized, clamp arm (44) may be pivoted relative to ultrasonic blade(100) to grasp and manipulate tissue without cutting or damaging thetissue.

In some versions, an electrical current may also be provided throughultrasonic blade (100) and clamp arm (44) to also cauterize the tissue.While some configurations for an acoustic transmission assembly andtransducer assembly (12) have been described, still other suitableconfigurations for an acoustic transmission assembly and transducerassembly (12) will be apparent to one or ordinary skill in the art inview of the teachings herein. Similarly, other suitable configurationsfor end effector (40) will be apparent to those of ordinary skill in theart in view of the teachings herein.

In the present example, shaft assembly (30) is configured to selectivelycouple with transducer assembly (12). To assist in proper coupling, atorque wrench (not shown) may be included about shaft assembly (30).Such a torque wrench may be configured to facilitate gripping of shaftassembly (30) as shaft assembly (30) is rotated relative to transducerassembly (12) during coupling. In addition, such a torque wrench may beconfigured to provide audible and/or tactile feedback once theappropriate amount of torque as been achieved to provide a coupling oftransducer assembly (12) and shaft assembly (30) at the appropriatetightness. For instance, a torque wrench may provide a pair of audibleand tactile clicks once the appropriate level of torque/tightness hasbeen achieved. Other variations of a torque wrench will be apparent tothose of ordinary skill in the art in view of the teachings herein.Furthermore, it should be understood that a torque wrench may simply beomitted, if desired.

In some versions, shaft assembly (30) includes an articulation sectionenabling end effector (40) to be angularly deflected laterally away fromthe longitudinal axis defined by shaft assembly (30). By way of exampleonly, such an articulation section may be configured in accordance withone or more teachings of U.S. Pub. No. 2012/0078247, the disclosure ofwhich is incorporated by reference herein. As another merelyillustrative example, such an articulation section may be configured inaccordance with one or more teachings of U.S. patent application Ser.No. 13/538,588 and/or U.S. patent application Ser. No. 13/657,553, thedisclosures of which are incorporated by reference herein. Of course,some versions of shaft assembly (30) may simply lack articulationaltogether. Shaft assembly (30) of the present example comprises a knob(32) that is operable to rotate shaft assembly (30) and end effector(40) relative to handle assembly (20), about the longitudinal axis ofshaft assembly (30). However, it should be understood that knob (32) androtatability of shaft assembly (30) are merely optional.

The foregoing components and operabilities of instrument (10) are merelyillustrative. Instrument (10) may be configured in numerous other waysas will be apparent to those of ordinary skill in the art in view of theteachings herein. By way of example only, at least part of instrument(10) may be constructed and/or operable in accordance with at least someof the teachings of any of the following, the disclosures of which areall incorporated by reference herein: U.S. Pat. No. 5,322,055; U.S. Pat.No. 5,873,873; U.S. Pat. No. 5,980,510; U.S. Pat. No. 6,325,811; U.S.Pat. No. 6,773,444; U.S. Pat. No. 6,783,524; U.S. Pub. No. 2006/0079874;U.S. Pub. No. 2007/0191713; U.S. Pub. No. 2007/0282333; U.S. Pub. No.2008/0200940; U.S. Pub. No. 2009/0105750; U.S. Pub. No. 2010/0069940;U.S. Pub. No. 2011/0015660; U.S. Pub. No. 2012/0112687; U.S. Pub. No.2012/0116265; U.S. patent application Ser. No. 13/538,588; U.S. patentapplication Ser. No. 13/657,553; and/or U.S. Pat. App. No. 61/410,603.Additional variations for instrument (10) will be described in greaterdetail below. It should be understood that the below describedvariations may be readily applied to any of the instruments referred toin any of the references that are cited herein, among others.

II. Exemplary Ultrasonic Blade Configuration

FIGS. 2-9 show ultrasonic blade (100) of instrument (10) in greaterdetail. Ultrasonic blade (100) of the present example is in the form ofa tapered multi-functional curved blade with functional asymmetries andminimized undesirable motion. It should be understood that providing acurved version of ultrasonic blade (100) introduces a set of engineeringconsiderations that may need to be addressed. For instance, a curvedultrasonic blade (100) may need to be properly balanced, includingcareful positioning of the mass along end effector (40). Another aspectof proper balancing may include a desire to separately balanceorthogonal displacements encountered by an activated ultrasonic blade(100), which may be particularly challenging when blade (100) is curved.In addition, a curved ultrasonic blade (100) may be prone to fracturedue to high stresses in the curved region of blade (100), particularlyif blade (100) comes into contact with metal when blade (100) is in anactivated state. Furthermore, a curved ultrasonic blade (100) mayprovide a relatively shorter active length, which may in turn limit thesize of the vessel (or other tissue structure) that may be operated onby blade (100). (“Active length” may be defined as the as the lengthfrom the distal end (102) of blade (100) to where the displacement isone half of the displacement at its distal end (102).) Blade (100) ofthe present example accounts for the foregoing considerations.

With the above-noted engineering considerations addressed, it shouldalso be understood that the curved and tapered configuration of blade(100) may provide surgical benefits such as improved surgeon visibility.In addition, the curve and taper may together provide a longer activelength through increased speed of sound and progressive reduction inmass. Also, the taper may results in a smaller surface at distal end(102), which may improve piercing/dissection capability by increasinglocal pressure imparted on tissue. Robust performance may be improved bycontrolling the ratio of acoustic stress to bending stress in theexposed portion of blade (100). Blade (100) may thus be less sensitiveto damage from inadvertent contact with other metallic material forimproved life.

Blade (100) of the present example is positioned at the distal end ofwaveguide (150). The proximal end of waveguide (150) is coupled withtransducer assembly (12). Thus, blade (100) and waveguide (150) togetherdefine an acoustic transmission assembly that is acoustically coupledwith transducer assembly (12). By way of example only, this acoustictransmission assembly may be approximately 36 cm in length,approximately 23 cm in length, or any other suitable length. In thepresent example, distal end (102) of ultrasonic blade (42) is located ata position corresponding to an anti-node associated with resonantultrasonic vibrations communicated through waveguide (150), in order totune the acoustic transmission assembly to a preferred resonantfrequency f_(o) when the acoustic transmission assembly is not loaded bytissue. Blade (100) and waveguide (150) are integrally formed in thisexample, though blade (100) and waveguide (150) may alternatively beformed as separate pieces that are joined together (e.g., through athreaded coupling, interference fit, welded joint, etc.). Blade (100)may be understood to effectively terminate proximally at the distal-mostnode associated with resonant ultrasonic vibrations communicated throughwaveguide (150). In other words, blade (100) extends from thedistal-most node to the distal-most anti-node.

When transducer assembly (12) is energized, distal end (102) ofultrasonic blade (100) is configured to move longitudinally (along thex-axis) in the range of, for example, approximately 10 to 500 micronspeak-to-peak, and in some instances in the range of about 20 to about200 microns, at a predetermined vibratory frequency f_(o) of, forexample, 55.5 kHz. When transducer assembly (12) of the present exampleis activated, these mechanical oscillations are transmitted throughwaveguide (150) to reach ultrasonic blade (100), thereby providingoscillation of ultrasonic blade (100) at the resonant ultrasonicfrequency. Thus, when tissue is secured between ultrasonic blade (100)and clamp arm (44), the ultrasonic oscillation of ultrasonic blade (100)may simultaneously sever the tissue and denature the proteins inadjacent tissue cells, thereby providing a coagulative effect withrelatively little thermal spread.

Blade (100) of the present example is tapered from its proximal endtoward distal end (102). Blade (100) is also curved such that the centerof distal end (102) is positioned lateral to the longitudinal axisdefined by waveguide (150). It should be understood that certain balancefeatures may be required to maintain longitudinal motion substantiallyalong the x-axis and within the x-y plane and also to separatetransverse mode ranges of vibration away from the desired longitudinalmode of vibration at a resonant frequency of 55.5 kHz. As will bedescribed in greater detail below, waveguide (150) includes a series ofgain steps that are configured to provide a gain of approximately 3.5,such that distal end (102) of blade (100) will vibrate along the x-axisat a maximum excursion of approximately 73.5 microns at maximum powergeneration (e.g., such that the excursion of transducer (150) isapproximately 21.5 microns).

The taper of blade (100) is best seen in FIGS. 7-9, which shows a set ofcross-sections at various locations along the length of blade (100). Inparticular, FIG. 7 shows a proximal cross-section of blade (100) along aplane that runs along an axis (PA) that is perpendicular to thelongitudinal axis of waveguide (150). FIG. 8 shows an intermediatecross-section of blade (100) along a first plane that is obliquelyoriented relative to the axis (PA). FIG. 9 shows a distal cross-sectionof blade (100) along a second plane that is obliquely oriented relativeto the axis (PA). In the present example, the width of blade (100) inthe cross-section shown in FIG. 7 is between about 0.055 inches andabout 0.070 inches, and more particularly between about 0.060 inches andabout 0.065 inches. The width of blade (100) in the cross-section shownin FIG. 8 is between about 0.045 inches and about 0.060 inches, and moreparticularly between about 0.050 inches and about 0.055 inches. Thewidth of blade (100) in the cross-section shown in FIG. 9 is betweenabout 0.035 and 0.050 inches, and more particularly between about 0.040inches and about 0.045 inches. Of course, any other suitable dimensionsmay be used.

The curves and taper blade (100) are defined by simple radial cuts, aswell as more complex compound radii cuts, which are made in a basecurved cylinder. These cuts define a plurality of balance features (110,112, 114, 120). In particular, and as best seen in FIG. 4, a firstbalance feature (110) is formed by a lateral concave cut having a firstradius of curvature (R1). By way of example only, the first radius ofcurvature (R1) may be between about 0.200 inches and about 0.250 inches,and more particularly about 0.225 inches. Of course, any other suitablevalue may be used for the first radius of curvature (R1). In the presentexample, first balance feature (110) is defined by the first radius ofcurvature (R1) swept along an orthogonal x-y plane that passes throughthe longitudinal axis of shaft assembly (30). A second balance feature(112) is formed by a lateral concave cut having a second radius ofcurvature (R2) swept along an orthogonal x-y plane that passes throughthe longitudinal axis of shaft assembly (30). By way of example only,the second radius of curvature (R2) may be between about 0.250 inchesand about 0.275 inches, and more particularly about 0.268 inches. Ofcourse, any other suitable value may be used for the second radius ofcurvature (R2). In the present example, second balance feature (112) isoffset from first balance feature (110) along the length of blade (100).In particular, second balance feature (112) is located further distalthan first balance feature (110) by between about 0.002 inches and about0.010 inches, and more particularly about 0.005 inches. Alternatively,any other suitable offset (or no offset at all) may be used. In thepresent example, second balance feature (112) is defined by the secondradius of curvature (R2) swept along the same orthogonal x-y plane thatpasses through the longitudinal axis of shaft assembly (30) as theorthogonal x-y plane associated with first balance feature (110) andfirst radius of curvature (R1).

A third balance feature (114) extends circumferentially about blade(100) and is formed by a concave cut having a third radius of curvature(R3). By way of example only, the third radius of curvature (R3) may bebetween about 0.600 inches and about 0.700 inches, and more particularlyabout 0.650 inches. Of course, any other suitable value may be used forthe third radius of curvature (R3).

A fourth balance feature (120) is best seen in FIGS. 4 and 7-8. Fourthbalance feature (120) is formed as a longitudinally extending convexrecess in one corner of blade (100). The recess of balance feature (120)is defined by a fourth radius of curvature (R4) that is swept along thex-y plane and a fifth radius of curvature (R5) that is swept along they-z plane. By way of example only, the fourth radius of curvature (R4)may be between approximately 1.350 inches and approximately 1.425inches, and more particularly about 1.395 inches. Alternatively, anyother suitable value may be used for the fourth radius of curvature(R4). In the present example, the x-y plane along which the fourthradius of curvature (R4) is swept is parallel to yet spaced apart fromthe x-y plane along which the first and second radii of curvature (R1,R2) are swept. Also by way of example only, the fifth radius ofcurvature (R5) may be between approximately 0.060 inches andapproximately 0.065 inches, and more particularly about 0.062 inches.Alternatively, any other suitable value may be used for the fifth radiusof curvature (R5). Fourth balance feature (120) may be configured tobalance motion of blade (100) as described in U.S. Pat. No. 6,773,444,the disclosure of which is incorporated by reference herein. Inaddition, fourth balance feature (120) presents an edge (122) that maybe used to back-cut tissue and/or for other purposes. In some versionsof instrument (10) that have clamp arm (44), ultrasonic blade (100) isoriented such that edge (122) faces toward clamp arm (44). In some otherversions of instrument (10) that have clamp arm (44), ultrasonic blade(100) is oriented such that edge (122) faces away from clamp arm (44).

As can be seen in FIG. 4, the lateral concave cut of second balancefeature (112) transitions into a convex curve extending to distal end(102). This convex curve is defined by a sixth radius of curvature (R6)swept along an orthogonal x-y plane that passes through the longitudinalaxis of shaft assembly (30). By way of example only, the sixth radius ofcurvature (R6) may be approximately 1.446 inches. Of course, any othersuitable value may be used for the sixth radius of curvature (R6).

FIG. 10 shows an exemplary alternative ultrasonic blade (200) that maybe located at the distal end of waveguide (150). Blade (200) of thisexample is substantially similar to blade (100) described above andincludes a distal end (202) and a plurality of balance features (210,212, 214, 220). In some versions, blade (100) is approximately 36centimeters in length while blade (200) is approximately 23 centimetersin length. Of course, any other suitable dimensions may be used. Thedifferences in the radii of curvature associated with blade (200) may beselected to account for blade (200) having a shorter length than blade(100).

In the example shown in FIG. 10, balance features (210, 212) of blade(200) are substantially identical to respective balance features (110,112) of blade (100), including having the same radii of curvature asbalance features (110, 112). While balance feature (220) of blade (200)is also similar to balance feature (120) of blade (100), balance feature(220) is defined by radii of curvature (R7, R8) that differ from therespective radii of curvature (R4, R5) that define balance feature(120). In particular, the recess of balance feature (220) is defined bya seventh radius of curvature (R7) that is swept along the x-y plane andan eighth radius of curvature (R8) that is swept along the y-z plane. Byway of example only, the seventh radius of curvature (R7) may be betweenapproximately 1.390 inches and approximately 1.500 inches, and moreparticularly about 1.420 inches. In some other versions, the seventhradius of curvature (R7) is approximately 1.395 inches. Alternatively,any other suitable value may be used for the seventh radius of curvature(R7). Also by way of example only, the eighth radius of curvature (R8)may be between approximately 1.000 inches and approximately 1.200inches, and more particularly about 1.100 inches. In some otherversions, the eighth radius of curvature (R8) is approximately 1.395inches. Alternatively, any other suitable value may be used for theeighth radius of curvature (R8).

Blade (200) of FIG. 10 also has a circumferentially extending balancefeature (214) defined by a ninth radius of curvature (R9) that isapproximately 1.500 inches. Alternatively, any other suitable value maybe used for the ninth radius of curvature (R9). The lateral concave cutof balance feature (212) transitions into a convex curve extending todistal end (202). This convex curve is defined by a tenth radius ofcurvature (R10) swept along an orthogonal x-y plane that passes throughthe longitudinal axis of shaft assembly (30). By way of example only,the tenth radius of curvature (R10) may be approximately 1.395 inches.Of course, any other suitable value may be used for the tenth radius ofcurvature (R10). As noted above, in some instances an ultrasonic bladehaving a length of approximately 36 cm is configured in accordance withblade (100); while an ultrasonic blade having a length of approximately23 cm is configured in accordance with blade (200). Alternatively, theconfiguration of either blade (100, 200) may be combined with any othersuitable ultrasonic blade length.

FIGS. 11-12 show waveguide (150) of the present example in greaterdetail. Waveguide (150) may be flexible, semi-flexible or rigid.Waveguide (150) may also be configured to amplify the mechanicalvibrations transmitted through waveguide (150) to blade (100) as is wellknown in the art. Waveguide (150) may further have features to controlthe gain of the longitudinal vibration along waveguide (150) andfeatures to tune waveguide (150) to the resonant frequency of thesystem. In particular, waveguide (150) may have any suitablecross-sectional dimension. For example, waveguide (150) may be taperedat various sections to control the gain of the longitudinal vibration.Waveguide (150) may, for example, have a length substantially equal toan integral number of one-half system wavelengths (nλ/2). The waveguide(150) and blade (100) may be preferably fabricated from a solid coreshaft constructed out of material, which propagates ultrasonic energyefficiently, such as titanium alloy (e.g., Ti-6Al-4V), aluminum alloys,sapphire, stainless steel or any other acoustically compatible material.Waveguide (150) may further include at least one radial hole or aperture(not shown) extending therethrough, substantially perpendicular to thelongitudinal axis of waveguide (150). Such an aperture may be positionedat a node. A proximal o-ring (not shown) and distal o-ring (130) (seeFIGS. 2-6) are assembled onto the acoustic transmission assembly nearthe ultrasonic nodes of waveguide (150), as is known in the art.

As further shown in FIGS. 11-12, waveguide (150) further includesbalance features (160). Balance features (160) are formed as laterallypresented flat surfaces on waveguide (150), which is otherwisecylindraceous. Balance features (160) serve to widen the transverse moderanges away from the preferred longitudinal modes in both directionsfrom the resonant frequency (e.g., 55.5 kHz). In some versions, balancefeatures (160) are spaced 180° apart on waveguide (150) and extend for alength from about 2.600 inches to about 2.800 inches, and moreparticularly about 2.700 inches. The centerline of balance features(160) is from about 7.000 to about 7.200 inches, and more particularlyabout 7.148 inches. Alternatively, any other suitable dimensions may beused.

III. Exemplary Control Circuits

In some instances, instrument (10) may include a foot pedal (not used)that provides a switch for selectively energizing transducer (12) andultrasonic blade (100). Alternatively, the operator may use buttons (26)as switches to selectively energize transducer (12) and ultrasonic blade(100). In some such instances, however, there may be significantvariability in the resistance of cable (14) and/or in the resistance ofcontacts in circuitry between generator (16) and buttons (26). Suchvariable resistance may make it difficult for generator (16) to detectswitch closure states (e.g., when buttons (26) are depressed).Variability in resistance may be due to residue left on contacts ofhandle assembly (20) by a cleaning process; and/or due to other factors.Some versions of the circuitry may be significantly less susceptible tosuch risks. For instance, some versions of circuitry may effectivelynull out the effects of variable resistance in real time. Variousexamples of such circuitry are described in greater detail below; whilestill other examples will be apparent to those of ordinary skill in theart in view of the teachings herein.

In some versions, generator (16) comprises a GENII generator,manufactured and sold by Ethicon Endo-Surgery, Inc. Generator (16) mayact as a constant-current source (e.g., at approximately +/−16 mA,alternating at a low frequency, such as about 500 Hz) and determine thestate of the switches (open/closed) in handle assembly (20) by measuringthe voltage drop across the handswitch lines, at the face of generator(16). This voltage drop may include an unknown voltage drop caused bythe resistance in cable (14) and/or resistance at contacts in handleassembly (20), which may change over time due to factors such asinstrument rotation and changes in contact force during instrumentusage, etc. The examples described below enable generator (16) todetermine and subtract out this unknown voltage drop by measuring aknown reference component in handle assembly (20) that produces a knownvoltage drop, in close time proximity to measuring the switch states.

FIG. 13 shows one merely exemplary circuit (200) that may beincorporated into instrument (10) to account for variations inresistance as described above. Circuit (200) includes a referenceresistor (210) and an EEPROM (212) that together provide a referencefeature placed on the positive leg of circuit (200). This referencefeature formed by reference resistor (210) and EEPROM (212) may be readon the positive half-cycle of an interrogation signal from generator(16). It should be understood that EEPROM (212) draws such low currentthat EEPROM (212) will not appreciably affect the voltage drop producedby reference resistor (210). Circuit (200) also includes a set ofswitches (220), respective resistors (222), and a pair of diodes (224).Switches (220) are actuated by buttons (26), trigger (28), and/or othermovable features in handle assembly (20). Switches (220), resistors(222), and diodes (224) are placed on the negative leg of circuit (200).Switches (220), resistors (222), and diodes (224) are thus read on thenegative half-cycle of an interrogation signal from generator (16).Generator (16) is operable to determine and subtract out a voltage dropfrom switches (220), resistors (222), and diodes (224) based on a knownvoltage drop from reference resistor (210), in close time proximity tomeasuring the states of switches (220).

FIG. 14 shows another merely exemplary circuit (300) that may beincorporated into instrument (10) to account for variations inresistance as described above. Circuit (300) includes a reference zenerdiode (310) and an EEPROM (312) that together provide a referencefeature placed on the positive leg of circuit (300). This referencefeature formed by reference zener diode (310) and EEPROM (312) may beread on the positive half-cycle of an interrogation signal fromgenerator (16). It should be understood that EEPROM (312) draws such lowcurrent that EEPROM (312) will not appreciably affect the voltage dropproduced by zener diode (310). Circuit (300) also includes a set ofswitches (320), respective diodes (322), and an additional pair ofdiodes (324). Switches (320) are actuated by buttons (26), trigger (28),and/or other movable features in handle assembly (20). Switches (320)and diodes (322, 324) are placed on the negative leg of circuit (300).Switches (320) and diodes (322, 324) are thus read on the negativehalf-cycle of an interrogation signal from generator (16). Generator(16) is operable to determine and subtract out a voltage drop fromswitches (320) and diodes (322, 324) based on a known voltage drop fromreference zener diode (310), in close time proximity to measuring thestates of switches (320).

FIG. 15 shows another merely exemplary circuit (400) that may beincorporated into instrument (10) to account for variations inresistance as described above. Circuit (400) is substantially similar tocircuit (300) described above, in that circuit (400) includes areference zener diode (410), an EEPROM (412), switches (420), and diodes(422, 424) that are all arranged in a manner similar to the arrangementof zener diode (310), EEPROM (312), switches (320), and diodes (322,324) of circuit (300). Unlike circuit (300), circuit (400) of thisexample further includes a turn-on delay circuit (430). Turn-on delaycircuit (430) is set to approximately ¼ of the interrogation signalcycle-time of generator (16), so that generator (16) sees only thereference feature (i.e., zener diode (410) and EEPROM (412)) during thefirst half of the negative half-cycle; and then sees switches (420), anddiodes (422, 424) in parallel with the reference feature during thesecond half of the negative half-cycle. In some versions, turn-on delaycircuit (430) may include a Maxim MAX6895 sequencer driving a PhilipsPMV65XP p-channel FET. Other suitable configurations for turn-on-delaycircuit (430) will be apparent to those of ordinary skill in the art inview of the teachings herein.

FIG. 16 shows another merely exemplary circuit (500) that may beincorporated into instrument (10) to account for variations inresistance as described above. Circuit (500) is substantially similar tocircuit (200) described above, in that circuit (200) includes areference resistor (510), an EEPROM (512), switches (520), resistors(522), and diodes (524) that are all arranged in a manner similar to thearrangement of reference resistor (210), an EEPROM (212), switches(220), resistors (222), and diodes (224) of circuit (200). Unlikecircuit (200), circuit (500) of this example further includes a turn-ondelay circuit (530). Turn-on delay circuit (530) is set to approximately¼ of the interrogation signal cycle-time of generator (16), so thatgenerator (16) sees only the reference feature (i.e., reference resistor(510) and EEPROM (512)) during the first half of the negativehalf-cycle; and then sees switches (520), resistors (522), and diodes(524) in parallel with the reference feature during the second half ofthe negative half-cycle. In some versions, turn-on delay circuit (530)may include a Maxim MAX6895 sequencer driving a Philips PMV65XPp-channel FET. Other suitable configurations for turn-on-delay circuit(530) will be apparent to those of ordinary skill in the art in view ofthe teachings herein.

FIG. 17 shows another merely exemplary circuit (600) that may beincorporated into instrument (10) to account for variations inresistance as described above. Circuit (600) is substantially similar tocircuit (500) described above, in that circuit (600) includes areference resistor (610), an EEPROM (612), switches (620), resistors(622), and diodes (624) that are all arranged in a manner similar to thearrangement of reference resistor (510), an EEPROM (512), switches(520), resistors (522), and diodes (524) of circuit (500). Circuit (600)also includes a turn-on delay circuit (630), which may be configured andoperable just like turn-on delay circuit (530) described above. However,in this example turn-on delay circuit (630) is inserted at the oppositeend of switch (620) ladder. Such positioning of turn-on delay circuit(630) may allow the use of an output stage that employs an n-channel FETor an essentially open-drain integrated circuit (e.g., a Zetex ZSCT1555low-voltage 555 timer).

FIG. 18 shows exemplary input and output waveforms of turn-on delaycircuits (430, 530, 630). In particular, signal A represents an inputsignal for turn-on delay circuit (430, 530, 630); while signal Brepresents an output signal for turn-on delay circuit (430, 530, 630).

FIG. 19 shows another merely exemplary circuit (700) that may beincorporated into instrument (10) to account for variations inresistance as described above. Circuit (700) is substantially similar tocircuit (400) described above, in that circuit (300) includes areference zener diode (710), an EEPROM (712), switches (720), and diodes(722, 724) that are all arranged in a manner similar to the arrangementof zener diode (410), EEPROM (412), switches (420), and diodes (422,424) of circuit (400). Unlike circuit (400), circuit (700) of thisexample further includes a toggle circuit (730) in place of turn-ondelay circuit (430). Toggle circuit (730) of this example is a flip-floptype of circuit that is triggered by a second pulse during the negativehalf-cycle, and reset by the positive pulse on the positive half-cycle.While not shown, it should be understood that toggle circuit (730) mayalternatively be positioned at the opposite end of the switch (720)ladder (e.g., similar to the placement of turn-on delay circuit (630) incircuit (600). FIG. 20 shows exemplary input and output waveforms oftoggle circuit (730). In particular, signal C represents an input signalfor toggle circuit (730); while signal D represents an output signal fortoggle circuit (730).

It should be understood that the circuits (200, 300, 400, 500, 600, 700)described above are merely illustrative examples. Various other suitablecomponents, features, and techniques may be used to alternately switchin a reference feature alone, and then either a switch ladder inparallel with the reference feature, or by itself. It should also beunderstood that the number of switches (220, 320, 420, 520, 620, 720)may vary; such that more than three switches (220, 320, 420, 520, 620,720) or less than three switches (220, 320, 420, 520, 620, 720) may beused.

IV. Exemplary Single-Use Features

At least one or more portions of some versions of instrument (10) may besterilized and reused. For instance, it may be desirable to reclaim andreuse electrical components within handle assembly (20), such ascircuits, etc. However, it may be undesirable for other portions ofhandle assembly (20) to be re-used, such as the outer housing of handleassembly (20), buttons (26), etc. Thus, it may be desirable to configurehandle assembly (20) such that some components within handle assembly(20) may be reclaimed and re-used; yet such that other portions ofhandle assembly (20) may not be reclaimed and re-used. In some settings,at least a portion of instrument (10) may be re-used after instrument(10) has been used in a surgical procedure. In some other settings, atleast a portion of instrument (10) may be re-used before instrument (10)even leaves a manufacturing facility. For instance, if an instrument(10) fails a quality control test, one or more components of theinstrument (10) (e.g., those that had no impact on the quality controltest failure) may be reclaimed and re-used to build another instrument(10). Several examples of configurations that may be incorporated intohandle assembly (20) to provide selective reusability will be describedin greater detail below; while still other examples will be apparent tothose of ordinary skill in the art in view of the teachings herein.

In some versions of instrument (10), at least part of the circuitry mayinclude a flex circuit that is formed as a laminate. One or more regionsof the outer layer of this laminate may be adhered to the housing ofhandle assembly (20), such that one or more layers are pulled away fromthe flex circuit when the housing is disassembled during a reclamationprocess, such that the flex circuit would be damaged. Such pulling awayof layers may render the flex circuit inoperable. In some suchinstances, an entire outer layer of a circuit is adhered to the housingof handle assembly (20). In some other instances, only portions of thecircuit near key circuit components are adhered to the housing of handleassembly (20). As another variation, one or more components of thecircuit may be adhered to the housing of handle assembly (20), withoutnecessarily adhering the flexible laminate of a flex circuit to thehousing of handle assembly (20). In some such versions, the flexiblelaminate of the flex circuit may be perforated or otherwise weakened,providing a controlled breakage region such that the flex circuit tearsaway from the adhered circuit component while the adhered circuitcomponent remains with the housing of the handle assembly when thehandle assembly portions are pulled apart during an attemptedreclamation. As yet another merely illustrative example, one or moreregions of a circuit in handle assembly (20) may be sensitive to water,alcohol, or other fluid, such that the circuit is destroyed when suchregions come into contact with water, alcohol, or other fluid that maybe used during an attempted reclamation. For instance, a circuitlaminate may be configured to delaminate upon contact with water,alcohol, or other fluid.

FIGS. 21-25 show an exemplary handle housing assembly (1000) that may beincorporated into instrument (10). Assembly (1000) of this exampleincludes a first housing member (1010), a second housing member (1030),and a retention member (1050). As best seen in FIG. 21, housing member(1010) includes a plurality of posts (1012) and a socket (1014). As alsobest seen in FIG. 21, housing member (1030) includes a plurality ofsockets (1032) and a post (1034). Posts (1012, 1034) are configured forinsertion into corresponding sockets (1014, 1032) to secure housingmembers (1010, 1030) together. By way of example only, posts (1012,1034) may be press-fit into corresponding sockets (1014, 1032), may besecured in sockets (1014, 1032) using ultrasonic welding, may beheat-staked in sockets (1014, 1032), may be adhered in sockets (1014,1032) using adhesive, and/or may be otherwise secured relative tosockets (1014, 1032). As best seen in FIGS. 22-23, housing members(1010, 1030) also include complementary tongue-and-groove features(1018, 1038). In some other versions, tongue-and-groove features (1018,1038) are replaced with complementary shiplap features or some otherkind of structures. Tongue-and-groove features (1018, 1038) may besecured together through interference fitting, ultrasonic welding,heat-staking, adhesive, etc.

As also best seen in FIGS. 22-23, housing members (1010, 1030) eachinclude a weakened strip (1016, 1036) in the form of a v-shaped cutout.Weakened strips (1016, 1036) provide reduced wall thicknesses thatpromote breakage along weakened strips (1016, 1036) when housing members(1010, 1030) are pulled apart. In other words, when a person attempts toseparate joined housing members (1010, 1030) by pulling joined housingmembers (1010, 1030) apart, one or both of housing members (1010, 1030)may break its respective weakened strip (1016, 1036). Thus, a fragmentof one housing member (1010, 1030) may remain joined to the otherhousing member (1010, 1030) while the rest of the fragmented housingmember (1010, 1030) may be free from the other housing member (1010,1030). This breakage/fragmentation may prevent re-use of both housingmembers (1010, 1030). The smaller fragment of the broken housing member(1010, 1030) may remain joined to the other housing member (1010, 1030)due to the secure relationship between tongue-and-groove features (1018,1038), between socket (1014) and post (1034), and/or otherwise. Othersuitable ways in which controlled breakage may be provided in housingmembers (1010, 1030) will be apparent to those of ordinary skill in theart in view of the teachings herein.

As best seen in FIG. 25, retention member (1050) of the present examplegenerally has a “Y” shape, with a first branch (1052), a second branch(1054), and a third branch (1056). First branch (1052) includes a bentsection (1058) and a recess (1070) that terminates at an edge (1072).Second and third branches (1054, 1056) each have respective posts(1060). As best seen in FIGS. 21 and 24, retention member (1050) isconfigured to fit in retention member features (1020, 1040) of housingmembers (1010, 1030). As shown in FIG. 23, retention member feature(1020) of housing member (1010) comprises a pair of sockets (1022) thathave a hexagonal profile. Sockets (1022) are configured to receive posts(1060) through an interference fitting. Of course, sockets (1022) mayhave any other suitable configuration; and ultrasonic welding,heat-staking, adhesive, etc., may also be used to secure posts (1060) insockets (1022). As shown in FIGS. 22 and 24, retention member feature(1040) of housing member (1030) comprises a pair of snap latch members(1042). Retention member (1050) may be slid into position behind snaplatch members (1042), such that snap latch members (1042) may assist inmaintaining the positioning of retention member (1050) relative tohousing member (1030). As shown, bent section (1058) of retention member(1050) passes between and in front of snap latch members (1042) whenbranches (1054, 1056) are positioned behind snap latch members (1042).

In the present example, one or more switch assemblies (not shown) arepositioned behind buttons (26), and include switching circuitry that isresponsive to actuation of buttons (26). Recess (1070) is sized toreceive a portion of such a switch assembly. In particular, a switchassembly may be slid between bent section (1058) of first branch (1052)and snap latch members (1042), with the switch assembly being receivedin recess (1070). Snap latch members (1042) assist in holding the switchassembly in position relative to housing member (1030). A pair of ribs(1043) defined in housing member (1010) also hold the switch assemblyagainst housing member (1030). Thus, one outer edge of the switchassembly is retained by snap latch members (1042) while the oppositeouter edge of the switch assembly, which is seated in recess (1070), isretained by retention member (1050). Since retention member (1050) issecured to housing member (1010), it should be understood that retentionmember (1050) and snap latch members (1042) will exert opposing forceson the outer edges of the switch assembly as housing members (1010,1030) are pulled apart. These opposing surfaces on the switch assemblymay sever/break the switch assembly (e.g., by shearing) or otherwiserender it in operable. Thus, if a person attempts to disassembly handleassembly (1000) by pulling housing members (1010, 1030) apart, doing sowill also destroy the switch assembly that is located behind buttons(26). The switch assembly may comprise any suitable components such asrigid circuit boards, flexible circuits, wires, conventional switches,etc. In some instances, edge (1072) is sharp to facilitate severing ofthe switch assembly.

While snap latch members (1042) retain the switch assembly relative tohousing member (1030) in the present example, it should be understoodthat a switch assembly may be otherwise retained relative to housingmember (1030). For instance, at least part of the switch assembly may bewelded to housing member (1030) (e.g., using spin welding, ultrasonicwelding, heat-staking, adhesives, etc.). As another merely illustrativeexample, a secondary retention feature may be overlaid about recess(1070) of retention member (1050). As yet another merely illustrativeexample, the switch assembly may be adhered to housing member (1030).Other suitable ways in which a switch assembly may be secured will beapparent to those of ordinary skill in the art in view of the teachingsherein.

FIG. 26 shows another exemplary handle housing assembly (1100) that maybe incorporated into instrument (10). Assembly (1100) of this exampleincludes a first housing member (1110) and a second housing member(1130). Housing member (1110) includes a plurality of posts (1112) and asocket (1114). Housing member (1130) includes a plurality of sockets(1132) and a post (1134). Posts (1112, 1134) are configured forinsertion into corresponding sockets (1114, 1132) to secure housingmembers (1110, 1130) together. By way of example only, posts (1112,1134) may be press-fit into corresponding sockets (1114, 1132), may besecured in sockets (1114, 1132) using ultrasonic welding, may beheat-staked in sockets (1114, 1132), may be adhered in sockets (1114,1132) using adhesive, and/or may be otherwise secured relative tosockets (1114, 1132).

Housing member (1110) includes an integral retention feature (1150) thatcomprises a pair of prongs (1152). Prongs (1152) define a gap configuredto receive a portion of a switch assembly, which may include switchingcircuitry that is responsive to actuation of buttons (26). An adhesivemay be used to adhere the switch assembly to prongs (1152). In instanceswhere housing assembly (1100) is disassembled, the switch assembly maybe retained in retention feature (1150). It should be understood that,due to the adhesion of the switch assembly in retention feature (1150),a person who is assembling several housing assemblies (1100) may be ableto quickly identify housing assembly (1100) as one that had already beenassembled and perhaps later disassembled. This may prompt the person todiscard the housing assembly (1100) as scrap. In addition, an adhesivemay be used to adhere the switch assembly to an adjacent region ofhousing member (1130). Thus, when housing assembly (1100) isdisassembled by pulling housing members (1110, 1130) apart, the switchassembly may be ripped apart and thereby rendered inoperable. Again, iftwo torn-apart switch assembly fragments remain adhered to each housingmember (1110, 1130), a person who is assembling several housingassemblies (1100) may be able to quickly identify housing assembly(1100) as one that had already been assembled and later disassembled.

In some instances, it may be desirable to carefully disassemble a handleassembly (20) while minimizing destruction of handle assembly (20). Forinstance, this may be done to salvage at least a portion of handleassembly (20) and/or something within handle assembly (20). With someversions of handle assembly (20), this may be accomplished by carefullydrilling one or more holes in handle assembly (20). For instance, FIG.27 shows an example where a hole (1200) may be drilled in a housingmember (1010, 1110) at a location corresponding to post (1034, 1134) andsocket (1014, 1114), thereby effectively decoupling post (1034, 1134)and socket (1014, 1114). FIG. 28 shows an example where holes (1210,1220) are drilled in a housing member (1030) at locations correspondingto posts (1060) and sockets (1022), thereby effectively decoupling posts(1060) and sockets (1022). Of course, housing members (1010, 1030, 1110,1130) may be drilled in numerous other locations, including thoseassociated with posts (1012, 1112) and sockets (1032, 1132). The drilledholes may facilitate separation of housing member (1010, 1110) fromhousing member (1030, 1130) with minimal force, may substantiallymaintain structural integrity of housing members (1010, 1110, 1030,1130), and/or may minimize damage to components within housing members(1010, 1110, 1030, 1130). In instances where a drilled housing member(1010, 1110, 1030, 1130) may be re-used, the drilled hole may be filledin, covered, or otherwise dealt with.

FIGS. 29-30 show an exemplary ultrasonic blade assembly (1300)comprising an ultrasonic blade (1310) disposed in a tube (1320).Ultrasonic blade (1310) is positioned such that a distal end (1312) ofblade (1310) is exposed relative to tube (1320). Tube (1320) has aninner diameter that is substantially greater than the outer diameter ofblade (1310), such that a cylindraceous gap is defined between the innerdiameter of tube (1320) and the outer diameter of blade (1310). Anannular overmold (1330) is positioned about the exterior of blade (1310)to support blade (1310) relative to tube (1320). By way of example only,overmold (1330) may be formed of a plastic material or an elastomericmaterial. Overmold (1330) may be located at a longitudinal positioncorresponding to a node associated with resonant ultrasonic vibrationscommunicated through blade (1310). The positioning and/or properties ofovermold (1330) provide substantial acoustic isolation of tube (1320)relative to blade (1310). While one overmold (1330) is shown, it shouldbe understood that several overmolds may be used. It should also beunderstood that features other than overmold (1330) may be used. By wayof example only, one or more o-rings located at nodes may be usedinstead of overmold (1330).

Tube (1320) includes a distally directed tab (1322) formed by a“U”-shaped cut in tube (1320). As best seen in FIG. 30, tab (1322) isdirected inwardly and distally within tube (1320). In the presentexample, tab (1322) does not contact ultrasonic blade (1310). In someother versions, tab (1322) contacts ultrasonic blade (1310) at a nodeassociated with resonant ultrasonic vibrations communicated throughblade (1320). Tab (1322) is resilient such that tab (1322) deflects outof the way when blade (1310) and overmold (1330) are inserted distallythrough tube (1320) during assembly of ultrasonic blade assembly (1300);yet tab (1322) returns back to the position shown in FIG. 30 afterovermold (1330) clears tab (1322). However, if blade (1310) and overmold(1330) are retracted proximally through tube (1320) during disassemblyof ultrasonic blade assembly (1300), tab (1322) will tear throughovermold (1330) or otherwise destroy overmold (1330). To the extent thatsomeone attempts to later re-use blade (1310) and overmold (1330), thedestroyed overmold (1330) would cause the rebuilt ultrasonic bladeassembly (1300) to fail a leak test.

In some versions of instrument (10), transducer assembly (12) may besupported within handle assembly (20) by a connector housing thatpermits transducer assembly (12) to rotate relative to handle assembly(20), about the longitudinal axis defined by transducer assembly (12).FIGS. 31-32 show an example of such a connector housing (1400) alongwith exemplary features that may be used to couple connector housing(1400) to handle assembly (20). In particular, connector housing (1400)of this example includes a retention boss (1410) that defines an opening(1412). One housing half of the handle includes a retention clip (1420);while another housing half of the handle includes a pair of retentionflanges (1430). Retention clip (1420) includes a pair of barbed arms(not shown). The barbed arms are configured to fit through opening(1412) of retention boss (1410) and thereby provide a snap fit betweenconnector housing (1400) and the associated housing half of the handle,as shown in the transition from FIG. 31 to FIG. 32. Flanges (1430) areconfigured to partially encompass connector housing (1400) and therebyrestrict movement of connecting housing (1400) to some degree; yet stillpermit connector housing (1400) to float within the handle assembly tosome degree.

In another example a first clamshell half (not shown) and a secondclamshell half (not shown) join together to encompass a connectorhousing (not shown) that is similar to connector housing (1400)described above. The joined halves may couple with handle assembly (20)through gripper pins, adhesive, ultrasonic welding, some other form ofwelding, or in any other suitable fashion. The joined halves may or maynot move relative to handle assembly (20). However, the joined halvesmay enable the connector housing to float relative to the joined halvesas needed. As another merely illustrative variation, a silicone membermay be interposed between the connector housing and handle assembly (20)instead of joined halves. Such a silicone member may substantiallyretain the connector housing within handle assembly (20) yet stillpermit some degree of movement (i.e., floating) of the connector housingrelative to handle assembly (20). Other suitable ways in which aconnector housing may be coupled with a handle assembly will be apparentto those of ordinary skill in the art in view of the teachings herein.These connector housing coupling features may be used in conjunctionwith any of the features described above to provide a way of recognizinga used switch assembly or shroud.

V. Miscellaneous

It should be understood that any of the versions of instrumentsdescribed herein may include various other features in addition to or inlieu of those described above. By way of example only, any of theinstruments described herein may also include one or more of the variousfeatures disclosed in any of the various references that areincorporated by reference herein. It should also be understood that theteachings herein may be readily applied to any of the instrumentsdescribed in any of the other references cited herein, such that theteachings herein may be readily combined with the teachings of any ofthe references cited herein in numerous ways. Other types of instrumentsinto which the teachings herein may be incorporated will be apparent tothose of ordinary skill in the art.

It should be appreciated that any patent, publication, or otherdisclosure material, in whole or in part, that is said to beincorporated by reference herein is incorporated herein only to theextent that the incorporated material does not conflict with existingdefinitions, statements, or other disclosure material set forth in thisdisclosure. As such, and to the extent necessary, the disclosure asexplicitly set forth herein supersedes any conflicting materialincorporated herein by reference. Any material, or portion thereof, thatis said to be incorporated by reference herein, but which conflicts withexisting definitions, statements, or other disclosure material set forthherein will only be incorporated to the extent that no conflict arisesbetween that incorporated material and the existing disclosure material.

Versions of the devices described above may have application inconventional medical treatments and procedures conducted by a medicalprofessional, as well as application in robotic-assisted medicaltreatments and procedures. By way of example only, various teachingsherein may be readily incorporated into a robotic surgical system suchas the DAVINCI™ system by Intuitive Surgical, Inc., of Sunnyvale, Calif.Similarly, those of ordinary skill in the art will recognize thatvarious teachings herein may be readily combined with various teachingsof U.S. Pat. No. 6,783,524, entitled “Robotic Surgical Tool withUltrasound Cauterizing and Cutting Instrument,” published Aug. 31, 2004,the disclosure of which is incorporated by reference herein.

Versions described above may be designed to be disposed of after asingle use, or they can be designed to be used multiple times. Versionsmay, in either or both cases, be reconditioned for reuse after at leastone use. Reconditioning may include any combination of the steps ofdisassembly of the device, followed by cleaning or replacement ofparticular pieces, and subsequent reassembly. In particular, someversions of the device may be disassembled, and any number of theparticular pieces or parts of the device may be selectively replaced orremoved in any combination. Upon cleaning and/or replacement ofparticular parts, some versions of the device may be reassembled forsubsequent use either at a reconditioning facility, or by a userimmediately prior to a procedure. Those skilled in the art willappreciate that reconditioning of a device may utilize a variety oftechniques for disassembly, cleaning/replacement, and reassembly. Use ofsuch techniques, and the resulting reconditioned device, are all withinthe scope of the present application.

By way of example only, versions described herein may be sterilizedbefore and/or after a procedure. In one sterilization technique, thedevice is placed in a closed and sealed container, such as a plastic orTYVEK bag. The container and device may then be placed in a field ofradiation that can penetrate the container, such as gamma radiation,x-rays, or high-energy electrons. The radiation may kill bacteria on thedevice and in the container. The sterilized device may then be stored inthe sterile container for later use. A device may also be sterilizedusing any other technique known in the art, including but not limited tobeta or gamma radiation, ethylene oxide, or steam.

Having shown and described various embodiments of the present invention,further adaptations of the methods and systems described herein may beaccomplished by appropriate modifications by one of ordinary skill inthe art without departing from the scope of the present invention.Several of such potential modifications have been mentioned, and otherswill be apparent to those skilled in the art. For instance, theexamples, embodiments, geometrics, materials, dimensions, ratios, steps,and the like discussed above are illustrative and are not required.Accordingly, the scope of the present invention should be considered interms of the following claims and is understood not to be limited to thedetails of structure and operation shown and described in thespecification and drawings.

I/We claim:
 1. An apparatus for operating on tissue, the apparatuscomprising: (a) a body; (b) an ultrasonic transducer operable to convertelectrical power into ultrasonic vibrations; (c) a shaft extendingdistally from the body, wherein the shaft defines a longitudinal axis;and (d) an end effector at the distal end of the shaft, wherein the endeffector comprises an ultrasonic blade in acoustic communication withthe ultrasonic transducer, wherein the ultrasonic blade includes arecess region having a plurality of recesses, wherein the recess regionis tapered such that the cross-sectional area of the recess regiondecreases along the length of the recess region.
 2. The apparatus ofclaim 1, wherein the ultrasonic blade is curved such that a centrallongitudinal axis of the ultrasonic blade extends along a curved path.3. The apparatus of claim 2, wherein the ultrasonic blade has a distaltip, wherein the distal tip is laterally offset relative to thelongitudinal axis defined by the shaft.
 4. The apparatus of claim 1,wherein the recesses include arcuate sections and longitudinallyextending sections.
 5. The apparatus of claim 4, wherein the arcuatesections are concave.
 6. The apparatus of claim 1, wherein the recessesinclude a first recess having a first arcuate section defined by a firstradius swept along a first orthogonal plane passing through thelongitudinal axis of the shaft, wherein the longitudinal axis of theshaft extends along the first orthogonal plane.
 7. The apparatus ofclaim 6, wherein the recesses further include a second recess having asecond arcuate section defined by a second radius swept along the firstorthogonal plane.
 8. The apparatus of claim 7, wherein the first andsecond arcuate sections are on opposite sides of the ultrasonic blade.9. The apparatus of claim 8, wherein the ultrasonic blade is curved suchthat a central longitudinal axis of the ultrasonic blade extends along acurved path, wherein the first arcuate section is positioned on aninside region of the curve of the ultrasonic blade, wherein the secondarcuate section is positioned on an outside region of the curve of theultrasonic blade.
 10. The apparatus of claim 6, wherein the recessesfurther include a third arcuate section defined in part by a thirdradius swept along a second orthogonal plane, wherein the secondorthogonal plane is parallel to the first orthogonal plane, wherein thesecond orthogonal plane is offset from the first orthogonal plane suchthat the longitudinal axis of the shaft does not extend along the firstorthogonal plane.
 11. The apparatus of claim 10, wherein the thirdarcutate section is further defined in part by a fourth radius sweptalong a third orthogonal plane, wherein the third orthogonal plane isperpendicular to the first and second orthogonal planes.
 12. Theapparatus of claim 10, wherein the first and third arcuate sectionsshare a common edge.
 13. The apparatus of claim 10, wherein the firstarcuate section proximally terminates at a first position along thelength of the ultrasonic blade, wherein the third arcuate sectionproximally terminates at a second position along the length of theultrasonic blade, wherein the second position is proximal relative tothe first position.
 14. The apparatus of claim 10, wherein part of thethird arcuate section terminates at a back-cutting edge.
 15. Theapparatus of claim 1, wherein the ultrasonic blade further comprises abalance feature formed by a concave cut extending circumferentiallyabout the ultrasonic blade.
 16. The apparatus of claim 1, wherein theend effector further comprises a clamp arm, wherein the clamp arm isselectively pivotable toward and away from the ultrasonic blade.
 17. Theapparatus of claim 16, wherein the ultrasonic blade includes aback-cutting edge, wherein the back-cutting edge faces toward the clamparm.
 18. An apparatus, comprising: (a) an surgical instrument, whereinthe surgical instrument includes one or more variable voltage dropfeatures configured to provide a variable voltage drop during operationof the surgical instrument; (b) a power source in communication with thesurgical instrument, wherein the power source is operable to providepower to the surgical instrument; and (c) a reference circuit incommunication with the surgical instrument, wherein the referencecircuit is further in communication with the power source, wherein thereference circuit includes one or more predetermined voltage dropfeatures configured to provide a predetermined voltage drop duringoperation of the surgical instrument; wherein the power source isoperable to subtract out a voltage drop from the one or more variablevoltage drop features based on a voltage drop from the one or morepredetermined voltage drop features during operation of the surgicalinstrument.
 19. The apparatus of claim 18, wherein the one or morepredetermined voltage drop features comprises a resistor or a diode,wherein the reference circuit further comprises a turn-on delay circuit.20. A method of operating a surgical instrument, the method comprising:(a) detecting a first voltage drop from the surgical instrument, whereinthe first voltage drop results from activation of a switch in thesurgical instrument, wherein the value of the first voltage drop isunknown; (b) detecting a second voltage drop from the surgicalinstrument, wherein the second voltage drop is caused by a referencecircuit component configured to provide a predetermined voltage dropsuch that the value of the second voltage drop is predetermined, whereinthe act of detecting the second voltage drop is performed in close timeproximity to the act of detecting the first voltage drop; and (c)providing power to the surgical instrument, wherein the act of providingpower to the surgical instrument comprises subtracting out the firstvoltage drop based on the second voltage drop.